count=0
def hanoi(n,src,dst,mid):
    global count
    if n==1 :
        print("{}:{}->{}".format(1,src,dst))
        count += 1
    else :
        hanoi(n-1,src,mid,dst)
        print("{}:{}->{}".format(n,src,dst))
        count += 1
        hanoi(n-1,mid,dst,src)
n=eval(input("请输入圆盘的数目"))
hanoi(n,"A","B","C")
print(count)